But,420,what is the title of the OP's post?Something about an AR-10,right?And he has a priority of long range accuracy,right?

You have been doing a rather hard sell,yes?

On pistons,take your choice,no problem.I,personally,would not consider a piston AR,so retro'ing to an M-14 is gas system is,IMO,not a step in the right direction for the purpose of long range accuracy.IMO,the good accuracy you achieve is in spite of,not due to,the piston system,and,for accuracy puroses,DI is inherently superior.

I will concede if horrible,filthy,charcoal and grit and coffee grounds ammo is used,a DI gun can get monkeyed up.

Precision ammo for a precision rifle,no problem.Varget burns quite clean in an AR.

But I had some ammo loaded with a recommended ball "Camp Perry" powder that ground my very dependable STG-58 to a stop in two mags.Quite piston.Good rifle ,anyway.Due to gas system,groups walk as it heats up.

I knew some folks who belonged to the Society for the Preservation of Colorful Anachronisms. Good folks!Fun! Quirky...but fun.

On prices,that may be because more and more outfits are producing the AR-10.Its becoming common,therefore,greater value for the buck,equals cheaper.
Whereas,the M-14 platform seems to be becoming more rare,therefore,collectable.

And...well,the time may be coming when the Curio and Relic folks and the NRA competition folks and the wood and steel M-14 folks might get all squinty eyed and call you Bubba.